altering climate
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ALTERING CLIMATEBasic ClimatologyOklahoma Climatological Survey
Funding provided by NOAASectoral Applications Research Project
ATMOSPHERIC POLLUTANTS
Acid Rain Acid Rain is the precipitation that carries higher-than-
normal amounts of nitric or sulfuric acid Actually includes dry deposition; some of these particles
may settle out of the atmosphere in the absence of rain ‘Neutral’ rain is slightly acidic (pH around 5.6) due to
naturally-occurring chemicals pH of 7.0 is neutral; less than that is considered acidic,
greater than that is alkaline Each 1.0 decrease in the scale indicates a 10-fold from
the next-higher number (e.g., water with a pH of 5.0 is 10 times more acidic than one with a pH of 6.0)
The most acidic rain in the U.S. (as of 2000 according to the EPA) had a pH of 4.3
Causes of Acid Rain: Volcanic eruptions Decomposition of organic matter Burning wood Burning fossil fuels
Main anthropogenic (man-made) sources are sulfur dioxide (SO2) and Nitrogen Oxides (NOx) emitted by power plants, industry, and automobiles
Source: NASA
Impacts of Acid Rain Surface Waters:
Kills or sickens fish and other food sources (such as insects) upon which they rely Excess nitrogen depletes oxygen (eutrophication), causing algae blooms and fish kills Leaches heavy metals, particularly aluminum, from the soil, which is toxic to many fish and plants Alkaline substances in the soil may counteract the effects of acid rain, but may become
overwhelmed May get a ‘shock’ with spring snowmelt, runoff
Forests: Acid buildup in soil weakens trees, making them more susceptible to other threats Dissolves and washes away nutrients Fog at higher elevations constantly bathe trees in acid, washing away nutrients
Materials: Causes blotches and fading of painted surfaces, including cars Deterioration of stone, particularly marble and limestone Corrosion of metals such as bronze and steel
Visibility: Molecules are larger and scatter more incoming light, reducing visibility Accounts for 50-70% of visibility reduction in the eastern U.S.
Human Health: Increase in heart and lung disorders, including asthma and bronchitis Causes an estimated $50 billion annually in premature mortality, hospital admissions, and
emergency room visits
Reducing Acid Rain Monitor and Report Reduce smokestack emissions
Remove sulfur at the source; clean coal Use scrubbers to remove SO2 before it leaves the smokestack
(chemical interactions that bind it with other substances that can be collected)
Use catalytic converters to remove NOx from automobile emissions Use alternative energy sources
Natural gas: still pollutes, but not as much Nuclear energy Hydropower Renewable energy: wind, solar, geothermal Electric vehicles
Restore damaged environments Limestone may be added to water to cancel out some of the acidity
on a short-term basis (but very expensive)
Ozone The ozone layer is a concentration of ozone (O3)
particles in the stratosphere Ozone is very good at absorbing harmful high-
energy ultraviolet radiation from the sun During the 1980s it was discovered that
chemicals, called chlorofluorocarbons (CFCs), were depleting the concentration of atmospheric ozone CFCs were commonly used in refrigeration, aerosol
sprays, and solvents One chlorine atom can break apart more than
100,000 ozone molecules The Montreal Protocol agreement in 1987 put in
place a ban on CFCs Alternative chemicals and technologies have been
developed to replace CFCs As a result of these actions, the ozone layer is
expected to recover by 2050
Source: NASA
But I Thought Ozone Was Good…
Up high, ozone filters harmful solar radiation… …but it’s not a good thing to breathe
Can worsen bronchitis, asthma, and emphysema Prolonged exposure can irritate and scar lung
tissue Ozone can also harm vegetation and
ecosystems and make trees more susceptible to disease
Ozone is created from Nitrogen Oxides (NOx) – the same bad guys as in acid rain
Ultraviolet radiation from the sun converts NOx near the surface into ozone Strong sunlight and high temperatures accelerate
the process Winds may carry emissions far from their sources,
so regions downwind may have similar air quality problems
Source: EPA
Carbon Dioxide Carbon Dioxide (CO2) is a critical component of the
Earth’s biosystems Used by plants to convert to sugars (energy) Plants release oxygen as a waste product, which animals
use Animals, in turn, release carbon dioxide as a waste product
However, high in the atmosphere, the radiative properties of CO2 cause trouble Relatively transparent to incoming solar radiation but a
good absorber of longer-wavelength radiation emitted by the Earth
CO2 essentially allows in the sun’s energy but traps the outgoing energy from the Earth, causing temperatures to rise in what is known as the Greenhouse Effect
Carbon dioxide has been building in the atmosphere as a byproduct of the combustion of fossil fuels – coal, oil, and natural gas Some CO2 is a good thing – recall that the Earth’s average
temperature would be about 0°F without it Other gasses can also add to the greenhouse effect,
particularly methane, which is a byproduct of agricultural production
Source: Washington Department of Ecology
HOW THEY AFFECT CLIMATE
Factors Affecting Climate Orbital Variations (millennia)
Eccentricity – the shape of the orbit around the sun (90,000-100,000 years) Obliquity – changes in the angle that Earth’s axis makes with the plane of Earth’s
orbit (40,000 years) Precession – the change in the direction of the Earth’s axis of rotation (25,800
years)
Factors Affecting Climate Orbital Variations (millennia) Solar Variations (decades)
A fairly regular 9-14 year (average 11) cycle in solar energy output, seen through the number of sunspots
Last solar maximum was in 2001; next is predicted for May 2013
Source: NASA
Factors Affecting Climate Orbital Variations (millennia) Solar Variations (decades) Oceanic Circulations (decades)
Periodic episodes of warming or cooling in different ocean basins May combine with other circulation patterns to reinforce or counteract other
climate trends
Source: NASA
Factors Affecting Climate Orbital Variations (millennia) Solar Variations (decades) Oceanic Circulations (decades) Volcanic Emissions (1-2 years)
Sulfate aerosols block solar radiation from surface, causing much lower temperatures (lasts 1-2 years)
Only eruptions whose plumes penetrate the lower stratosphere cause large variability; very few volcanoes do so
Source: NASA
Factors Affecting Climate Orbital Variations (millennia) Solar Variations (decades) Oceanic Circulations (decades) Volcanic Emissions (1-2 years) Change in Land Cover (gradual changes, affecting albedo)
Deforestation: more vegetation creates cooler, wetter surface conditions; less vegetation leads to warmer, drier conditions
Ice cover: more ice reflects more sunlight, leading to cooling; less ice allows more sunlight to be absorbed, warming the surface
Source: NASA,USDA
The recent warming is unusual…
…and solar variability cannot explain it
Droughts Wet!
Ice Storms
Oklahoma’s Winters Have Warmed
CLIMATE CHANGE PROJECTIONS
International Panel on Climate Change
IPCC Findings from 2007 Assessment: Higher confidence now exists in projected patterns of
warming than exists for other elements such as rainfall Hot extremes and heat waves will increase Heavy precipitation event frequency will continue to
increase Snow cover and sea ice continues to shrink Sea levels will rise, but uncertain as to how much and
timing Storm tracks are projected to move poleward Increasing acidification of the ocean Further 21st century emissions will contribute to
warming & sea level rise for more than a millennium
Societal response is key
Green Response
Middle Road
Maximum Growth
Societal Response
Temperature Projections: A Range of Possibilities
Annual U.S. precip will increase in
the northeast
and decrease in
the southwest
High Confidence
Oklahoma Projections Temperature (Middle Road scenarios)
Warming of 2-4°F in annual average temperature by the 2020s Warming of 4-7°F in annual average temperature by the 2090s Summer becomes longer and spring weather arrives earlier Winters warm – longer frost-free periods and a longer growing
season Earlier maturation of winter wheat and orchard crops leave them
more vulnerable to late freeze events Precipitation
Rain-free periods will increase, but individual rainfall events will be more intense
Increased year-round evaporation from the ground and transpiration from green vegetation
Drought frequency and severity increases The risk of wildfires increases, especially during summer
Oklahoma’s Water Future Fewer (but more intense) precipitation events:
More runoff, more flooding More pollution from runoff Increased erosion Crop damage
Increased temperatures will increase evaporation Will dry out more severely between precipitation
events Possibly less water available, even if yearly
totals increase
Winners and Losers
“There will be winners and losers from the impacts of climate change, even within a single region, but globally the losses are expected to far outweigh the benefits.” – from the National Academies’ report “Understanding and Responding to Climate Change”.
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